package com.lagou.edu.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 自定义springmvc拦截器
 */
public class MyInterceptor01 implements HandlerInterceptor {

    /**
     * 会在Handler方法业务逻辑执行之前执行
     * 往往在这里完成权限校验
     * @param request
     * @param response
     * @param handler
     * @return 返回值boolean代表是否放行，true代表放行，false代表终止
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("MyInterceptor01 preHandle....");
        String uri= request.getContextPath();
        HttpSession session = request.getSession();
        String username = (String) session.getAttribute("username");
        if(username!=null){
            System.out.println("用户登录，不拦截");
            return true;
        }else {
            System.out.println("没有用户登录，拦截！");
            response.sendRedirect("/index.jsp");
            return false;
        }
    }

    /**
     * 会在Handler方法业务逻辑执行之后尚未跳转页面时执行
     *
     * @param request
     * @param response
     * @param handler
     * @param modelAndView 封装了视图和数据，此时尚跳转页面，可以在这里针对返回的数据和视图信息进行修改
     * @return
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

        System.out.println("MyInterceptor01 postHandle....");
    }

    /**
     * 页面已经跳转渲染完毕之后执行
     * @param request
     * @param response
     * @param handler
     * @param ex 可以在这里捕获异常
     * @return
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

        System.out.println("MyInterceptor01 afterCompletion....");
    }
}
